Bond strengths of porcelain to cobalt-chromium alloys made by casting, milling, and selective laser melting.

STATEMENT OF PROBLEM: Cobalt-chromium (Co-Cr) alloys have been widely used for metal-ceramic fixed prostheses and can be fabricated using conventionally cast or new computer-aided technology. However, the effect of different manufacturing methods on the metal-ceramic bond strength needs further evaluation. PURPOSE: The purpose of this in vitro study was to evaluate the metal-ceramic bond strength of a Co-Cr alloy made by casting, milling, and selective laser melting (SLM). MATERIAL AND METHODS: Co-Cr specimens (25×3×0.5 mm) were prepared using a cast, milled, or SLM method and layered with ceramic (8×3×1.1 mm). Metal-ceramic bond strength was measured by a 3-point bend test according to ISO9693. The area fraction of adherence porcelain (AFAP) was determined by measuring the Si content of the specimens with scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS). The metal-ceramic bond strength and AFAP results were analyzed using 1-way analysis of variance and the Bonferroni post hoc test (α=.05). SEM/EDS and metallurgic microscopy were also used to study the specimens' morphology, elemental composition, and metallurgic structure. RESULTS: No significant differences (P>.05) were found for the bond strength among cast, milled, and SLM Co-Cr alloys. The milled and SLM groups showed significantly more porcelain adherence than the cast group (P<.001). The surface morphologies and oxidation characters of cast, milled, and SLM Co-Cr alloys were similar, whereas the metallurgic structures were different. CONCLUSIONS: The bond strength between ceramics and Co-Cr alloys is independent of the manufacturing method. However, milling- and SLM-produced alloys had better porcelain adherence.

The Effect of Reading Aloud Exercises for Complete Denture Patients during the Functional Rehabilitation Period.

PURPOSE: The focus of this study was to evaluate the effect of reading aloud on masticatory performance and patient satisfaction of patients rehabilitated with conventional complete dentures for the first time. MATERIALS AND METHODS: Sixty-two edentulous patients who received conventional complete denture treatment for the first time were randomly divided into two equal groups. After insertion of the dentures, patients in group I were asked to read a news report three times per day for 4 weeks, while those in group II did not read. The reading duration increased by 5 minutes per week, from 5 minutes in the first week to 20 minutes in the fourth week. The patients' mouth opening during reading aloud was advised to gradually increase throughout the training project. Two and four weeks after insertion of the dentures, masticatory performance was assessed using the sieving method, and patient satisfaction was measured using a visual analogue scale, which combined the patient's perceptions in relation to comfort, esthetics, stability, ability to talk, and ability to chew. RESULTS: There were significant improvements in masticatory performance with reading aloud exercises after the insertion of complete dentures (p < 0.001) at the 2- and 4-week follow-up visits. Masticatory performance also showed significant improvement within each group in the follow-up periods (p < 0.001). No significant differences were found between the two groups in patient satisfaction (p > 0.05) at 2 weeks, but at 4 weeks, patient satisfaction regarding stability, ability to talk, and ability to chew was significantly higher for group I (p < 0.001). CONCLUSIONS: The results of this study suggest that reading aloud exercises significantly improved early masticatory performance and patient satisfaction for denture wearers who were treated with conventional complete dentures for the first time, and may be a useful clinical application for more effective denture treatment.

Effect of silica coating on the bond strength of milled pure titanium to dental porcelain.

The creation of a high bond strength between machined computer-manufactured pure titanium and porcelain remains problematic, and the effects of a silica coating on the bond strength of milled pure titanium bonded to dental porcelain require further investigation. The objective of this study was to evaluate the bond strength of machined pure titanium, with an intermediate coating of silica, to dental porcelain. In this work, 24 specimens of milled pure titanium were prepared and randomly divided into test and control groups, in which the test group was coated with silica using the sol-gel dipping technique. The metal-ceramic bond strength was evaluated, according to ISO 9693 standards, using the three-point bending test, and scanning electron microscopy and energy-dispersive spectroscopy were used to study the microstructure and elemental composition of the specimens. The bonding strength of the silica-coated group was significantly higher than that of the control group, and more residual porcelain on the metal surface could be observed in the silica-coated group. Therefore, the application of a silica intermediate coating produced using the sol-gel method could significantly improve the bond strength between machined pure titanium and porcelain.

Novel Pickering bigels stabilized by whey protein microgels: Interfacial properties, oral sensation and gastrointestinal digestive profiles.

In the ongoing quest to formulate sensory-rich, low-fat products that maintain structural integrity, this work investigated the potential of bigels, especially those created using innovative Pickering techniques. By harnessing the unique properties of whey protein isolate (WPI) and whey protein microgel (WPM) as interfacial stabilizers, WPM-based Pickering bigels exhibited a remarkable particle localization at the interface due to specific intermolecular interactions. The rise in protein concentration not only intensified particle coverage and interface stabilization but also amplified attributes like storage modulus, yield stress, and adhesiveness, owing to enhanced intermolecular forces and a compact gel matrix. Impressively, WPM-based Pickering bigels outshone in practical applications, showcasing exceptional oil retention during freeze-thaw cycles and extended flavor release-a promising indication for frozen food product applications. Furthermore, these bigels underwent a sensory evolution from a lubricious texture at lower concentrations to a stable plateau at higher ones, offering an enriched consumer experience. In a comparative digestibility assessment, WPM-based Pickering bigels demonstrated superior prowess in decelerating the release of free fatty acids, indicating slowed lipid digestion. This study demonstrates the potential to fine-tune oral sensations and digestive profiles in bigels by modulating Pickering particle concentrations.

A preliminary study of aeolian sand-cement-modified gasification slag-paste backfill: Fluidity, microstructure, and leaching risks.

To realize low-cost green backfill mining, this paper proposes a novel model of aeolian sand-cement-modified gasification slag-paste backfill (ACGPB). This model realizes the safe disposal and resource utilization of hazardous solid wastes. A comprehensive experiment (including slump test, uniaxial compressive strength tests, microscopic test, and leaching toxicity tests) was conducted to explore how the mechanism of ACGPB depends on activator type and dosage. The results showed that fresh ACGPB slurry can be expressed by the Herschel-Bulkley model (R2 ≥ 0.965 in all recipes). With Na2SO4 as activator type, the yield stress, apparent viscosity, thixotropy, and slump of ACGPB slurry increased with increasing activator dosage. With CaO as activator type, the yield stress, apparent viscosity, thixotropy, and slump of ACGPB slurry fluctuated with increasing activator dosage. The mechanical properties of all recipes (not including Control group and C-C1) met the mechanical requirement (3 d ≥ 0.5 MPa and 28 d ≥ 1.0 MPa). In addition, the concentrations of all heavy metals remained within the range specified by the national standard. Specifically, the activator exerted a positive effect on the stabilization/solidification of heavy metal ions (Cu, Cd, Ba, Ni, Cr, Se, and As). Finally, FTIR, TG-DTG, SEM, and hydration heat were used to analyze the microstructure of ACGPB. The research results provide a creative way for the resource utilization of solid waste.

Preparation of ordered mesoporous carbons with an intergrown p6mm and cubic Fd3m pore structure using a copolymer as a template.

Ordered mesoporous carbons (OMCs) with an intergrown two-dimensional p6mm and three-dimensional Fd3m pore structure have been prepared by the carbonization of reverse copolymer-phenolic resin composites, which were themselves formed by a soft-template method by simply adjusting the ratios of ethanol and hexane. The microstructure of the OMCs was analyzed by small-angle X-ray scattering, nitrogen adsorption isotherms, and transmission electron microscopy. The results showed the structure of the OMCs obtained have the mesophase transition from p6mm to the intergrowth of p6mm/Fd3m and finally to Fd3m as the ratio of ethanol to hexane is changed.

A series of Zn-4f heterometallic coordination polymers and a zinc complex containing a flexible mixed donor dicarboxylate ligand.

A new zinc compound, together with a corresponding series of Zn-4f heterometallic coordination polymers, namely, [Zn(H2PBDA)(PBDA)]n (1), {[Ln2(PBDA)2·2H2O] [Zn2(PBDA)2Cl2]}n [H2PBDA = 3-(pyridin-3-yl-oxy) benzene-1,2-dicarboxylic acid, and Ln = Pr(2), Nd(3), Eu(4), Gd(5), Dy(6), Ho(7), Er(8)] have been hydrothermally synthesized and characterized systematically. Polymers 2-8 feature two-dimensional (2D) 4,4 networks, containing the original 1D heterometallic double stranded chains composed of [Ln2Zn2(PBDA)2] entities. The extensive hydrogen bonding and π-π stacking interactions were observed to stabilize the extended architectures. The luminescence emission spectra of the polymers vary depending on the lanthanide(III) ion present. Informative magnetic susceptibility measurements show that the same carboxylate bridging fashion of the PBDA ligand results in the different magnetic properties occurring within the heterometallic coordination polymers. In addition, polymer 6 exhibits an interesting slow magnetic relaxation behavior at lower temperatures.